Shulou(Shulou.com)06/02 Report--

In this issue, the editor will bring you about how to establish a virtual hosting service in ftp. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

Ftp is a set of standard protocols for file transfer over the network, using client / server mode. Based on TCP services only, UDP is not supported. FTP uses two ports, a data port and a command port (also known as a control port).

Like most Internet services, FTP is a client / server system. The user connects to the FTP server program on the remote host through a client program that supports the FTP protocol. The user issues a command to the server program through the client program, and the server program executes the command issued by the user and returns the result of the execution to the client.

For example, a user issues a command that requires the server to send a copy of a file to the user, and the server responds to this command by sending the specified file to the user's machine. The client program receives this file on behalf of the user and stores it in the user directory.

Active FTP

The active FTP is that the client connects to the command port (port 21) of the FTP server from an arbitrary unprivileged port N (N > 1024). Then the client starts listening on port Numb1 and sends the FTP command "port Number1" to the FTP server. The server then connects from its own data port (20) to the data port specified by the client (Number1).

Passive FTP

In order to solve the problem of the connection initiated by the server to the customer, a different way of FTP connection has been developed. Passive mode, which is enabled when the client notifies the server that it is in passive mode. In passive FTP, both command connection and data connection are initiated by the client, which can solve the problem that the incoming connection from the data port from the server to the client is filtered out by the firewall.

The above is the ftp shared by the editor on how to build a virtual hosting service. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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